摘要
研究了低取代度阳离子淀粉(CS-L)在Mg-Al类水滑石(HTlc)上的吸附行为。CS-L可在带结构正电荷的Mg-AlHTlc表面吸附,吸附方程符合Langmuir等温式,300min左右达吸附平衡,饱和吸附量为33.92mg/g。吸附驱动力可能缘自于:CS-L醚键或羟基与HTlc羟基之间形成氢键;熵效应,即吸附所引起的CS的熵减少小于被吸附水释放引起的熵增加。随着pH值的增加,CS-L和HTlc的Zeta电位均降低,二者静电排斥作用减小,吸附量增加;惰性电解质NaCl和CaCl2的加入可屏蔽HTlc与CS-L之间及CS-L分子内带正电的链段之间的静电排斥力,吸附量增加;pH=9时,带负电的Al八面体多聚体容易吸附在带结构正电荷的HTlc表面进而吸附CS分子,吸附量显著增加;温度升高降低二者氢键作用,吸附量降低。比较了CS-L与高取代度阳离子淀粉(CS-H)在Mg-AlHTlc上的吸附行为。
The adsorption of low-substituted cationic starch（ CS-L） on Mg-Al HTlc was investigated. The following results were obtained：CS-L can be adsorbed on the external surface of positively changed Mg-Al HTlc. The adsorption isotherm followed the typical Langmuir equation and the saturated adsorption amount was 33. 92 mg/g. The driving force for adsorption was probably due to two effects：（ 1） hydrogen bonding between the hydroxyl group or ether group of CS-L and the hydroxyl group of HTlc; （ 2） entropic effect,where the entropic loss for the CS-L adsorption is less then entropic gain for the released solvent molecules. The adsorption amount of CS-L increased with pH,which may be contributed to the decrease of the zeta potentials of CS-L and the HTlc with pH. The adsorption amount of CS-L increased with the addition of NaCl and CaCl2 because inert electrolytes screened the repulsion between HTlc particles and CS-L and the intra-molecular repulsion between the cationic groups of the CS-L. At pH = 9,the adsorption of CS-L on HTlc increased dramatically with the concentration of AlCl3 since the hydrolysate of Al3 ＋ might play a role as a linkage between CS-L and HTlc,and. The adsorption amount of CS-L decreased with increasing temperature as a result of hydrogen bonding decrease. The adsorption kinetics of CS-L on Mg-Al HTlc showed that the equilibrium time of adsorption was about 300 min. Furthermore,the comparison of adsorption behaviors between CS-L and CS-H on Mg-Al HTlc was also carried out.
出处
《应用化学》
CAS
CSCD
北大核心
2010年第7期811-816,共6页
Chinese Journal of Applied Chemistry
基金
国家自然科学基金(50772062)
国家重点基础研究发展(九七三)计划(2004CB418504)
山西省高校科技开发(20091038)资助项目
关键词
吸附
类水滑石化合物
低取代度
阳离子淀粉
adsorption
hydrotalcite analogue
low degree of substitution
cationic starch
